A NEW METHOD FOR THE DETERMINATION OF IODINE BY D. ROY McCULLAGH WITH THE TECHNICAL ASSISTANCE OF VALERIAN PICHA

Ever since the discovery of the element iodine by Courtois (1) in 1812 and the first clinical uses of this substance in the treatment of goiter by Prout (2) in 1816 and by Coindet (3) in 1820, almost continuous researches on the relationship of iodine to thyroid function have been in progress. The greatest obstacle in the way of these investigations has been the lack of a reliable method for the estimation of minute quantities of iodine. For instance, it was largely because of his unreliable chemical methods that Chatin (4), in 1853, was unable to convince his contemporaries that endemic goiter was caused by iodine deficiency. It was not until 1914 that a reliable method for the determination of iodine was introduced by Kendall (5). This method was satisfactory for materials such as the thyroid gland, containing large quantities of iodine, but could not be applied to the study of iodine in other tissues and in blood, unless enormous quantities were used. 10 years later, a method for the determination of iodine in organic material was devised by von Fellenberg (6) and later McClendon and coworkers (7) described another. These have led to definite advances in the knowledge of iodine metabolism, yet there are definite objections to both methods. McClendon’s method is accurate, but is too cumbersome for ordinary use; von Fellenberg’s suffers from the same handicap, and in addition, the results are likely to be unreliable because of loss of iodine heated in open crucibles. These methods and several modifications of the latter (8-12) have been tried in this laboratory, and all have been discarded as